Tired of “relaxing” coloring books that are basically just flowers and good vibes? This bold monochrome optical illusion coloring book is for the days when you want something satisfying , a little trippy, and way more fun than “breathe in, breathe out.” Inside you’ll find bold, easy-to-color op-art illusions designed for one-color coloring —thick, clean shapes with big open spaces, high contrast, and patterns that pop when you fill them in. No shading, no complicated palettes—just grab a marker or pen and watch the page come alive. Great for: Stress relief that keeps your brain entertained - One-color / limited-color coloring (monochrome lovers, this is your lane) - Quick, satisfying pages with a “whoa” payoff - Gifts for adults who love optical illusions, op-art, and bold designs Tip: For best results, use water-based markers or gel pens and place a spare sheet of paper or cardstock underneath to help prevent bleed-through.